This invention relates generally to utility metering systems of the type including a recorder for providing a recorded indication of a power outage condition to the recorder in conjunction with meter data and time interval information, and more particularly to such systems in which a master recorder contains circuitry for effecting the recording of a power outage indication by the master recorder and directing a plurality of slave recorders to record the same power outage indication.
Data recorders have been in use in the utility industry for years to accumulate meter pulse data on magnetic tape for later translation and calculation of power demand, billing and load survey. Typical recorders of this type are described in U.S. Pat. Nos. 3,913,129; 3,829,772; 3,375,526; 3,148,329; and 3,401,395. Another well known recorder for recording meter data pulses, time interval pulses and which records a power outage indication, is a demand recorder marketed by General Electric Company as the Model PDM-76 Demand Recorder and is disclosed in that Company's publication GEI-52489, entitled Maintenance Instructions, PDM-76 Demand Recorder. In the U.S. Pat. No. 3,913,129 and in the above GEI-52489 publication, recorders using magnetic tape cartridges capable of operating over extended recording periods are disclosed. In these recorders, when the beginning and the ending times of a recording period are known, a precise time record of the occurrence of the meter data is known by correlating real time to time interval pulses recorded by the recorders. Utilizing the data and time interval record on the tape, power consumption, maximum demand billing, and peak load information are conveniently calculated.
In the prior art, the aforementioned data recorders each contain their own circuitry for recording the data information, and the time interval and power outage indications. When measurements are to be from several meters, a separate recorder is required for each meter. In the systems of this type, several recorders are frequently used, and those recorders are all frequently powered from the same power source. As a result, they all operate from the same source to record their respective time interval information and they all stop simultaneously if there is a power outage. Additionally, they all operate from the same power source to individually write a power outage indication on their respective magnetic tapes when power is restored. The aforementioned recorders all function well to record the just described information, however, since each recorder is totally independent, containing its own circuitry for recording the interval and power outage information, it is expensive to the utilities, since a complete independent recorder must be purchased for each meter in the system. It is also difficult to synchronize the recorders, since each has its own timing circuit which must be individually set on time. To reduce the cost of recorders to the utility companies, a system of recorders is needed in which only one recorder, a master, contains all of the required time interval and power outage indication circuitry, and a plurality of other recorders, minus that circuitry, are slaved to the master recorder. In such a system, all of the recorders are synchronized with the master recorder to simultaneously record their respective meter data and the time interval and power outage indication information. The aforementioned PDM-76 demand recorder forms such a master recorder, and can serve as such in the present invention. Additionally, that recorder is suitably adaptable to serve as an economical slave recorder in a data recording system in accordance with the present invention.
Therefore, it is an object of the present invention to provide an improved data recording system of the type for providing time interval and power outage indications on a recording tape.
It is another object of the invention to provide a data recording system wherein a plurality of slave recorders are slaved to a master recorder to effect the synchronous recording of time interval and power outage information on the recording tape of each recorder.
A still further object of the invention is to provide a master recorder having recording circuitry for generating time and power outage information signals for recording information representative thereof by the master recorder and by at least one slave recorder not having the recording circuitry.